Dual Layer Winding Pattern

ABSTRACT

A dual-winding layer arrangement for a three-phase, four pole motor is provided.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/707,699, filed Feb. 18, 2010, the disclosure of which is incorporatedherein by reference for any and all purposes.

FIELD OF THE INVENTION

The present invention relates generally to electric motors and, moreparticularly, to a winding pattern that achieves the benefits of lapwinding and concentric winding.

BACKGROUND OF THE INVENTION

The trend towards designing and building fuel efficient, low emissionvehicles has increased dramatically over the last decade, withsignificant emphasis being placed on the development of hybrid andall-electric vehicles. This has led, in turn, to a greater emphasisbeing placed on electric motors, either as the sole source of propulsion(e.g., all-electric vehicles) or as a secondary source of propulsion ina combined propulsion system (e.g., hybrid or dual electric motorvehicles).

AC induction motors are well known and are used in a variety ofapplications ranging from industrial to automotive. In such a motor, amagnetic field is generated by a plurality of circumferentiallydistributed coil windings secured within a plurality ofcircumferentially distributed slots in the inner periphery of themotor's stator, the coil windings being coupled to an AC power source.The magnetic field generated within the stator core causes rotation ofthe motor's rotor, the rotor being comprised of one or more magneticpole pairs.

In general, the coil windings of the stator are divided into phases withthe number of phases typically equaling the number of phases of thepower supply. Each phase of the coil windings is then arranged into coilgroups, with each coil group representing a single pole of a singlephase. Each coil group is comprised of one or more individual coils orcoil windings. Thus a typical winding pattern for a single phase,two-pole induction motor will include two coil groups while athree-phase, two-pole induction motor will include six coil groups. Themanner in which the individual coil windings of the coil groups arearranged within the slots of the stator will determine, in part, theperformance characteristics of the motor as well as its manufacturingcost. Typically, one of two winding methodologies is used, referred toas concentric winding and lap winding.

Concentric winding is probably the most common winding methodology, atleast for those applications in which cost is a factor, since thismethodology is easily automated and therefore relatively cost effective.In a concentric arrangement, the individual coil windings comprisingeach coil group are concentrically arranged about the pole center withall of the windings within a group being positioned at the same radialdepth in their respective stator slots. While this approach can beautomated, such an arrangement typically results in unwanted spatialharmonics in the stator winding magnetomotive force (MMF) waveform,thereby affecting motor performance.

In lap winding, the other common winding method, a coil overlappingarrangement is applied in which the configuration of each coil issubstantially the same and in which one side of each coil overlaps aside of another coil. As a result of using substantially similar coilswith similar winding resistances, the electrical characteristics foreach phase are well balanced, thereby reducing the harmonic content inthe stator winding MMF waveform. Unfortunately, while this approachyields superior motor characteristics, it does not lend itself toautomation, resulting in a more costly manufacturing process.

Accordingly, what is needed is an electric motor winding arrangementthat achieves the benefits of lap winding, while lending itself toautomation. The present invention provides such a winding pattern and acorresponding automated manufacturing process.

SUMMARY OF THE INVENTION

The present invention provides a dual-layer winding arrangement for athree-phase, four pole motor and a method of manufacturing the same. Thefirst winding layer is comprised of six coil groups, and morespecifically of a first and a second first phase coil group, a first anda second second phase coil group and a first and a second third phasecoil group. The second winding layer is comprised of a second set of sixcoil groups, and more specifically of a third and a fourth first phasecoil group, a third and a fourth second phase coil group and a third anda fourth third phase coil group. The first and second first phase coilgroups comprise a first pole pair of the first phase, the third andfourth first phase coil groups comprise a second pole pair of the firstphase, the first and second second phase coil groups comprise a firstpole pair of the second phase, the third and fourth second phase coilgroups comprise a second pole pair of the second phase, the first andsecond third phase coil groups comprise a first pole pair of the thirdphase, and the third and fourth third phase coil groups comprise asecond pole pair of the third phase. Preferably the first inter-poleconnection electrically connecting the first and second first phase coilgroups is formed automatically by using a continuous wire/wire bundle toform the first and second first phase coil groups; preferably the secondinter-pole connection electrically connecting the first and secondsecond phase coil groups is formed automatically by using a continuouswire/wire bundle to form the first and second second phase coil groups;preferably the third inter-pole connection electrically connecting thefirst and second third phase coil groups is formed automatically byusing a continuous wire/wire bundle to form the first and second thirdphase coil groups; preferably the fourth inter-pole connectionelectrically connecting the third and fourth first phase coil groups isformed automatically by using a continuous wire/wire bundle to form thethird and fourth first phase coil groups; preferably the fifthinter-pole connection electrically connecting the third and fourthsecond phase coil groups is formed automatically by using a continuouswire/wire bundle to form the third and fourth second phase coil groups;and preferably the sixth inter-pole connection electrically connectingthe third and fourth third phase coil groups is formed automatically byusing a continuous wire/wire bundle to form the third and fourth thirdphase coil groups. The stator of the three-phase, four pole motor mayhave 60 slots. Each coil group may be comprised of three, four, five, ora different number of coils.

In at least one configuration, each coil group is arranged in aconcentric pattern with no overlap between the concentric coil groupscomprising the first winding layer and no overlap between the concentriccoil groups comprising the second winding layer, and with the firstwinding layer filling the lower portion of every stator slot and thesecond winding layer filling the upper portion of every stator slot. Thecoil groups in this configuration may be comprised of any number ofcoils, for example five coils, with each coil in each coil group being asingle turn coil.

In at least one alternate configuration, each coil group is comprised ofa plurality of coils, with one of the plurality being a double turncoil, and with the double turn coil for each coil group being positionedeither in the outermost coil position or in a slot adjacent to theoutermost coil position.

In at least one alternate configuration, each coil group is comprised ofa plurality of coils, with two of the plurality being double turn coils,and with one of the double turn coils of each coil group beingpositioned in the outermost coil position and with the other of thedouble turn coils of each coil group being positioned in a slot adjacentto the outermost coil position.

In at least one alternate configuration, the second first phase coilgroup overlaps the first first phase coil group; the second second phasecoil group overlaps the first second phase coil group; the second thirdphase coil group overlaps the first third phase coil group; the fourthfirst phase coil group overlaps the third first phase coil group; thefourth second phase coil group overlaps the third second phase coilgroup; and the fourth third phase coil group overlaps the third thirdphase coil group.

In at least one alternate configuration, three coils of the second firstphase coil group overlap three coils of the first first phase coilgroup; three coils of the second second phase coil group overlap threecoils of the first second phase coil group; three coils of the secondthird phase coil group overlap three coils of the first third phase coilgroup; three coils of the fourth first phase coil group overlap threecoils of the third first phase coil group; three coils of the fourthsecond phase coil group overlap three coils of the third second phasecoil group; and three coils of the fourth third phase coil group overlapthree coils of the third third phase coil group.

In at least one configuration, each coil group is arranged in a lapwinding pattern with no overlap between the individual coil groupscomprising the first winding layer and no overlap between the individualcoil groups comprising the second winding layer, and with the firstwinding layer filling the lower portion of every stator slot and thesecond winding layer filling the upper portion of every stator slot. Thecoil groups in this configuration may be comprised of any number ofcoils, for example five coils, with each coil in each coil group being asingle turn coil.

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the remaining portions of thespecification and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a stator slot with two windinglayers in place;

FIG. 2 provides the coil make-up for each winding layer of a firstpreferred embodiment;

FIG. 3 provides the coil make-up for each phase of the first preferredembodiment;

FIG. 4 diagrammatically illustrates the coil make-up for each phase ofthe first preferred embodiment;

FIG. 5 diagrammatically illustrates the coil configuration of a firstphase of the first preferred embodiment;

FIG. 6 illustrates the inter-pole connections of the three-phase, fourpole motor of the present invention;

FIG. 7 provides the coil make-up for each winding layer of a secondpreferred embodiment;

FIG. 8 provides the coil make-up for each phase of the second preferredembodiment;

FIG. 9 diagrammatically illustrates the coil configuration for eachphase of the second preferred embodiment;

FIG. 10 provides the coil make-up for each winding layer of a thirdpreferred embodiment;

FIG. 11 provides the coil make-up for each phase of the third preferredembodiment;

FIG. 12 diagrammatically illustrates the coil configuration for eachphase of the third preferred embodiment;

FIG. 13 provides the coil make-up for each winding layer of a fourthpreferred embodiment;

FIG. 14 provides the coil make-up for each phase of the fourth preferredembodiment;

FIG. 15 diagrammatically illustrates the coil configuration for eachphase of the fourth preferred embodiment;

FIG. 16 provides the coil make-up for each winding layer of a fifthpreferred embodiment;

FIG. 17 provides the coil make-up for each phase of the fifth preferredembodiment;

FIG. 18 diagrammatically illustrates the coil configuration for eachphase of the fifth preferred embodiment;

FIG. 19 provides the coil make-up for each winding layer of a sixthpreferred embodiment;

FIG. 20 provides the coil make-up for each phase of the sixth preferredembodiment;

FIG. 21 diagrammatically illustrates the coil configuration for eachphase of the sixth preferred embodiment; and

FIG. 22 provides the coil make-up for each winding layer of a seventhpreferred embodiment.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

The present invention utilizes a three-phase, four pole design with atwo layer winding insertion technique to achieve the motor performancecharacteristics commonly associated with lap winding along with the easeof manufacturing associated with concentric winding. In general, thepresent technique requires that the first winding layer be comprised ofthe coil groups for six individual poles, two per phase, and that thesecond winding layer be comprised of the coil groups for six individualpoles, two per phase. Within each layer, the two poles per phase aremembers of a pole pair, thereby forming the complementary poles (e.g.,north and south poles) of an electromagnet. Thus, for example, the firstlayer would include poles A1 and A2 of phase A while the second layerwould include poles A3 and A4 of phase A, where poles A1 and A2 comprisea first pole pair and poles A3 and A4 comprise a second pole pair, bothpole pairs associated with the same phase. Utilizing this approach, andas described and illustrated below, each winding layer can be fabricatedutilizing an only slightly modified concentric winding technique, thuslending itself to automation.

While the present invention may be used with patterns utilizing morethan two layers, the inventors have found that a two-layer design isoptimal as it allows excellent motor performance characteristics to beachieved while being simple enough to be automated. Accordingly, whilethe following examples only describe two-layer configurations, it willbe appreciated that the invention may also be applied to configurationswith more than two layers.

FIG. 1 is a cross-sectional view of a single slot 100 of a statorassembly, not shown. Prior to winding insertion, slot insulation liner101 is inserted within the slot. Next, and assuming that slot 100 is tobe filled with only two turns, the first turn of the first coil isinserted into the slot. In this example, this turn is comprised of abundle of insulated wires 103. It will be appreciated by those of skillin the art that the number and gauge of wires 103 depend upon thedesired motor characteristics. During fabrication, the next steprequires that wires 103 be pushed, or otherwise compacted, into slot100. After compaction, a phase insulation separator 105 is insertedwithin slot 100. If the first coil, comprised of wires 103, and thesecond coil, comprised of wires 107, are of the same phase, phaseinsulation separator 105 may not be required. Next, the second turn isinserted into slot 100, this turn being comprised of insulated wires107. As described and illustrated below, the second turn may be from thesame coil group or a different coil group. As previously noted withrespect to wires 103, each wire 107 may be comprised of multiple wirestrands, or a single wire strand. After a second compaction step, a slottop wedge 109 is inserted into slot 100 in order to ensure that thewires remain within the slot.

FIGS. 2-5 illustrate a first preferred embodiment of the invention. Thisconfiguration, as with the other illustrated embodiments, utilizes a60-slot stator. It should be understood, however, that the invention isnot limited to a 60-slot stator, rather, the inventors found that thisconfiguration yielded the desired motor performance without becoming toocomplex for automation. Other exemplary configurations utilize 48-slotstators (i.e., coil groups with 4 coils per group) and 72-slot stators(i.e., coil groups with 6 coils per group).

FIG. 2 illustrates the coil make-up for each winding layer. As shown, inthis embodiment each winding layer utilizes a relatively simpleconcentric winding pattern, with each coil group preferably comprised offive coils. Note that as used throughout this specification, the firstwinding layer, also simply referred to as the first layer, indicates thefirst set of coils inserted into the stator slots, where the first setof coils is comprised of the coil groups for six poles, two from eachphase. Similarly, the second winding layer, also simply referred to asthe second layer, indicates the second set of coils inserted into thestator slots, where the second set of coils is comprised of the coilgroups for the remaining six poles, two from each phase. It should beunderstood, and as will be illustrated in subsequent embodiments of theinvention, in some configurations a single winding layer (either thefirst or the second winding layer) may have two turns from the same coilgroup inserted within a single stator slot. In such a configuration,both turns are members of the same concentric coil group and are part ofthe same, single winding layer.

In FIG. 2, each winding layer is comprised of six concentric coil groupsin which there is no coil overlap. As previously described, the six coilgroups for each winding layer are comprised of two coil groups perphase, where the two same-phase coil groups per phase are from the samepole pair. In other words, the same-phase coil groups in a single layerare adjacent to one another and are complementary poles, i.e., comprisethe same pole pair. This aspect of the invention is illustrated in FIG.4, which shows the four coil groups per phase. This aspect is alsoillustrated in FIG. 5 in which the four coil groups for Phase A areillustrated in a 60-slot stator 501. As shown, coil groups A1 and A2 aremembers of one pole pair, i.e., they oppose each other in anelectromagnetic sense, while coil groups A3 and A4 comprise a secondpole pair. Note that coil groups A1 and A2 are part of the first windinglayer while coil groups A3 and A4 are part of the second winding layer.

As previously noted, in FIG. 2 both winding layers are shown. The firstwinding layer completely fills the lower portion of each of the statorslots, with no overlap and no skipped slots. Similarly, the secondwinding layer completely fills the slots, albeit the upper portion ofeach stator slot. Note that in FIG. 2, the phase designators for eachsecond layer coil are italicized and in bold.

FIG. 3 provides the coil winding information for each coil of the firstpreferred embodiment, i.e., configuration number 1, and as suchcorresponds to the data provided in FIG. 2. FIG. 3, however, providesthe specific stator slots for each coil, and thus the span distance foreach coil. For example, coil 1 of phase A goes from slot 1 to slot 15,spanning a distance of 14 slots. Similarly, coil 6 of phase A goes fromslot 30 to slot 16, therefore also spanning a distance of 14 slots. Thedirection of winding for these two coils, however, are opposite from oneanother, thus establishing opposing magnetic poles. Note that thewinding direction is indicated by the negative sign in front of the spandistance (e.g., as shown in the span columns for coil groups A2 and A4).

FIG. 4 diagrammatically provides the same information as given in FIG.3. The dotted lines in FIG. 4, e.g., line 401, represent inter-poleconnections. Note that due to the winding approach provided by theinvention, these inter-pole connections are accomplished during thewinding and coil insertion process, not after coil insertion as iscommon in prior art winding patterns. Thus, for example, the samecontinuous wire or wire bundle is used to first form the coils in the A1coil group, and then the coils in the A2 coil group, therebyautomatically forming the inter-pole connection during fabrication ofthe winding layer and eliminating the need for post-insertionfabrication of the inter-pole connection between these two coil groups.The elimination of the post-insertion inter-pole connection stepssimplifies motor production, thus reducing cost and motor complexitywhile improving motor reliability and quality. These same inter-poleconnections are also illustrated in FIG. 6, this figure providing thecoil group connections for the four pole, three phase configurations ofthe present invention.

FIGS. 7-9 illustrate a second preferred embodiment of the invention.FIG. 7 provides the coil information, per layer, and FIG. 8 provides thecorresponding detailed coil information. In this embodiment, while eachcoil group is comprised of five coils, two of the coils of each coilgroup are inserted into a single stator slot. Therefore in those slotsin which two turns of the same coil group are inserted, the slot isfilled during the insertion of a single winding layer (assuming atwo-turn configuration as is preferred). This aspect of this embodimentis shown in both FIGS. 7 and 8. See, for example, slot 1 in which twoturns of coil group A1 are inserted during the first winding layerfabrication step; similarly, slot 5 in which two turns of coil C3 areinserted during the second winding layer fabrication step. Note that inFIG. 9, which diagrammatically illustrates configuration 2, the doubleturn coils are shown in bold.

FIGS. 10-12 illustrate a third preferred embodiment of the invention. Asin the second embodiment, each coil group in this embodiment iscomprised of five coils, two coils of which are inserted within a singlestator slot. In this embodiment, the second outermost coil of each coilgroup is a double-turn coil, whereas in the second embodiment the firstoutermost coil of each group is the double-turn coil. Unlike the secondembodiment, however, in this embodiment during fabrication of a singlewinding layer there is limited overlap between coil groups. Morespecifically, during fabrication of each winding layer there are threeslots in which two different coil groups are inserted into the sameslot, i.e., slots 16, 36 and 56 in the first layer and slots 6, 26 and46 in the second layer.

FIGS. 13-15 illustrate a fourth preferred embodiment of the inventionthat also includes five coils per coil group. In this embodiment, withineach coil group there are two double-turn coils. More specifically andas shown, the first outermost coil of each group is a double-turn coilas with the second embodiment. Additionally, the second outermost coilof each coil group is also a double-turn coil, as with the thirdembodiment. This embodiment is similar to the second embodiment,however, in that during fabrication of a single winding layer there isno overlap between coil groups in that layer.

FIGS. 16-18 illustrate a fifth preferred embodiment of the invention. Aswith the first embodiment, each coil group in this embodiment iscomprised of five coils with no coil doubling within a group. Unlike thefirst embodiment, however, this embodiment does overlap coils fromdifferent coil groups during both the first and second layer fabricationsteps. For example, during insertion of the first winding layer, threeA2 coils are located on top of three A1 coils within slots 16-18.

FIGS. 19-21 illustrate a sixth preferred embodiment of the invention. Aswith the first and fifth embodiments, preferably each coil group in thisembodiment is comprised of five coils with no coil doubling within agroup. As with the first embodiment, in the sixth embodiment there is nooverlap between different coil groups during either the first or secondlayer fabrication steps. Unlike the previous embodiments, however, inthe sixth embodiment the coils within each coil group are completely lapwound. Accordingly, while the tables of FIGS. 2 and 19 are identical,the differences between embodiments one and six are illustrated in FIGS.20 and 21 which show the lap winding approach utilized for each coilgroup in the sixth embodiment.

The sixth embodiment lends itself to several different fabricationapproaches. In the preferred approach, which is similar to an approachapplicable to the above embodiments, pole pairs for each phase are firstfabricated, preferably using an automated winding machine. Preferablyeach pole pair is fabricated from a continuous wire/wire bundle so thatthe inter-pole connection between the two poles of each pole pair areformed automatically, thereby eliminating the need to form theseparticular inter-pole connections after insertion of the coils. Thus,for example, the pole pairs for coil groups A1 and A2 would be formedfrom a continuous wire/wire bundle; the pole pairs for coil groups A3and A4 would be formed from a second continuous wire/wire bundles; thepole pairs for coil groups B1 and B2 would be formed from a thirdcontinuous wire/wire bundle; etc. Next, and as shown in FIGS. 19-21, thefirst layer is inserted, the first layer comprised of coil groups A1,A2, B3, B4, C1 and C2. Then, phase insulation separators are inserted,as required, followed by insertion of the second layer comprised of coilgroups A3, A4, B1, B2, C3 and C4. After insertion of a retaining wedge,as required, external lugs and external connections are formed as notedin FIG. 6.

FIG. 22 illustrates a seventh configuration that is closely related tothe sixth embodiment. In this embodiment, a three winding layer designis used in which each layer is comprised of one phase. While threewinding layers are used, rather than two, the slot locations for thecoil groups of the seventh embodiment are the same as the coil groupslot locations in the sixth embodiment. However, and as noted below, thelocations within some of the stator slots is changed, e.g., changingbetween an upper slot location and a lower slot location. ThereforeFIGS. 20 and 21 remain unchanged between the sixth and seventhembodiments, but the table illustrated in FIG. 19 for the sixthembodiment is modified as shown in FIG. 22 in order to allow a completephase to be inserted in a single winding layer. In particular, and as aresult of this approach, coil groups A3, A4, B1 (slots 21-25), and B2(slots 36-40) are inserted into the lower portion, rather than the upperportion, of the stator slots as shown in FIG. 22. Similarly, in thisapproach coil groups B3 (slots 41-45), B4 (slots 56-60), C1 and C2 areinserted into the upper portion, rather than the lower portion, of thestator slots. An advantage of this approach is that it is possible towind all four coil groups for each phase from a continuous wire/wirebundle, thereby eliminating the inter-pole connections shown in FIG. 6(i.e., lugs A, B and C).

In the accompanying figures, it should be understood that identicalelement symbols used on multiple figures refer to the same component, orcomponents of equal functionality. Additionally, the accompanyingfigures are only meant to illustrate, not limit, the scope of theinvention.

As will be understood by those familiar with the art, the presentinvention may be embodied in other specific forms without departing fromthe spirit or essential characteristics thereof. Accordingly, thedisclosures and descriptions herein are intended to be illustrative, butnot limiting, of the scope of the invention which is set forth in thefollowing claims.

1. A three-phase, four pole electric motor, comprising: a stator with aplurality of slots; a first winding layer contained within at least afirst subset of said plurality of slots, wherein said first windinglayer is comprised of a first set of six coil groups, wherein said firstset of six coil groups is comprised of a first and a second first phasecoil group, a first and a second second phase coil group, and a firstand a second third phase coil group; a second winding layer containedwithin at least a second subset of said plurality of slots, wherein saidsecond winding layer is comprised of a second set of six coil groups,wherein said second set of six coil groups is comprised of a third and afourth first phase coil group, a third and a fourth second phase coilgroup, and a third and a fourth third phase coil group; and wherein saidfirst and second first phase coil groups comprise a first pole pair ofsaid first phase, wherein said third and fourth first phase coil groupscomprise a second pole pair of said first phase, wherein said first andsecond second phase coil groups comprise a first pole pair of saidsecond phase, wherein said third and fourth second phase coil groupscomprise a second pole pair of said second phase, wherein said first andsecond third phase coil groups comprise a first pole pair of said thirdphase, and wherein said third and fourth third phase coil groupscomprise a second pole pair of said third phase.
 2. The three-phase,four pole electric motor of claim 1, further comprising: a firstinter-pole connection electrically connecting said first first phasecoil group to said second first phase coil group, wherein said firstfirst phase coil group and said second first phase coil group are formedfrom a first continuous wire or wire bundle such that said firstinter-pole connection is automatically formed during fabrication of saidfirst winding layer, and wherein said automatic formation of said firstinter-pole connection eliminates post-insertion fabrication of saidfirst inter-pole connection; a second inter-pole connection electricallyconnecting said first second phase coil group to said second secondphase coil group, wherein said first second phase coil group and saidsecond second phase coil group are formed from a second continuous wireor wire bundle such that said second inter-pole connection isautomatically formed during fabrication of said first winding layer, andwherein said automatic formation of said second inter-pole connectioneliminates post-insertion fabrication of said second inter-poleconnection; a third inter-pole connection electrically connecting saidfirst third phase coil group to said second third phase coil group,wherein said first third phase coil group and said second third phasecoil group are formed from a third continuous wire or wire bundle suchthat said third inter-pole connection is automatically formed duringfabrication of said first winding layer, and wherein said automaticformation of said third inter-pole connection eliminates post-insertionfabrication of said third inter-pole connection; a fourth inter-poleconnection electrically connecting said third first phase coil group tosaid fourth first phase coil group, wherein said third first phase coilgroup and said fourth first phase coil group are formed from a fourthcontinuous wire or wire bundle such that said fourth inter-poleconnection is automatically formed during fabrication of said secondwinding layer, and wherein said automatic formation of said fourthinter-pole connection eliminates post-insertion fabrication of saidfourth inter-pole connection; a fifth inter-pole connection electricallyconnecting said third second phase coil group to said fourth secondphase coil group, wherein said third second phase coil group and saidfourth second phase coil group are formed from a fifth continuous wireor wire bundle such that said fifth inter-pole connection isautomatically formed during fabrication of said second winding layer,and wherein said automatic formation of said fifth inter-pole connectioneliminates post-insertion fabrication of said fifth inter-poleconnection; and a sixth inter-pole connection electrically connectingsaid third third phase coil group to said fourth third phase coil group,wherein said third third phase coil group and said fourth third phasecoil group are formed from a sixth continuous wire or wire bundle suchthat said sixth inter-pole connection is automatically formed duringfabrication of said second winding layer, and wherein said automaticformation of said sixth inter-pole connection eliminates post-insertionfabrication of said sixth inter-pole connection.
 3. The three-phase,four pole electric motor of claim 1, wherein said stator has 60 slots.4. The three-phase, four pole electric motor of claim 1, wherein eachcoil group of said first set of six coil groups and said second set ofsix coil groups is comprised of five coils.
 5. The three-phase, fourpole electric motor of claim 1, wherein each coil group of said firstwinding layer is arranged in a concentric pattern, wherein there is nooverlap between the concentric coil groups comprising said first windinglayer, wherein said first winding layer fills a lower portion of everyslot of said plurality of slots, wherein each coil group of said secondwinding layer is arranged in a concentric pattern, wherein there is nooverlap between the concentric coil groups comprising said secondwinding layer, and wherein said second winding layer fills an upperportion of every slot of said plurality of slots.
 6. The three-phase,four pole electric motor of claim 5, wherein each coil group of saidfirst and second winding layers is comprised of a plurality of coils,wherein each of said plurality of coils for each coil group is a singleturn coil.
 7. The three-phase, four pole electric motor of claim 5,wherein each coil group of said first and second winding layers iscomprised of a set of five coils, wherein each coil of each set of fivecoils is a single turn coil.
 8. The three-phase, four pole electricmotor of claim 1, wherein each coil group of said first and secondwinding layers is comprised of a plurality of coils, wherein one of saidplurality of coils for each coil group is a double turn coil.
 9. Thethree-phase, four pole electric motor of claim 8, wherein said doubleturn coil for each coil group of said first and second winding layerscorresponds to an outermost coil position for that coil group.
 10. Thethree-phase, four pole electric motor of claim 8, wherein said doubleturn coil for each coil group of said first and second winding layerscorresponds to a coil position adjacent to an outermost coil positionfor that coil group.
 11. The three-phase, four pole electric motor ofclaim 1, wherein each coil group of said first and second winding layersis comprised of a set of four coils, wherein three coils of each set offour coils is a single turn coil, wherein one coil of each set of fourcoils is a double turn coil, and wherein said double turn coilcorresponds to an outermost coil position for that coil group.
 12. Thethree-phase, four pole electric motor of claim 1, wherein each coilgroup of said first and second winding layers is comprised of a set offour coils, wherein three coils of each set of four coils is a singleturn coil, wherein one coil of each set of four coils is a double turncoil, and wherein said double turn coil corresponds to a coil positionadjacent to an outermost coil position for that coil group.
 13. Thethree-phase, four pole electric motor of claim 1, wherein each coilgroup of said first and second winding layers is comprised of aplurality of coils, and wherein each plurality of coils is comprised ofa first double turn coil and a second double turn coil.
 14. Thethree-phase, four pole electric motor of claim 13, wherein said firstdouble turn coil for each coil group of said first and second windinglayers corresponds to an outermost coil position for that coil group,and wherein said second double turn coil for each coil group of saidfirst and second winding layers corresponds to a coil position adjacentto said outermost coil position for that coil group.
 15. Thethree-phase, four pole electric motor of claim 1, wherein each coilgroup of said first and second winding layers is comprised of a set ofthree coils, wherein a first coil of each set of three coils is a singleturn coil, wherein a second coil of each set of three coils is a firstdouble turn coil that corresponds to an outermost coil position for thatcoil group, and wherein a third coil of each set of three coils is asecond double turn coil that corresponds to a coil position adjacent tosaid outermost coil position for that coil group.
 16. The three-phase,four pole electric motor of claim 1, wherein each coil group of saidfirst winding layer is arranged in a concentric pattern and each coilgroup of said second winding layer is arranged in a concentric pattern,wherein said second first phase coil group overlaps said first firstphase coil group, wherein said second second phase coil group overlapssaid first second phase coil group, wherein said second third phase coilgroup overlaps said first third phase coil group, wherein said fourthfirst phase coil group overlaps said third first phase coil group,wherein said fourth second phase coil group overlaps said third secondphase coil group, and wherein said fourth third phase coil groupoverlaps said third third phase coil group.
 17. The three-phase, fourpole electric motor of claim 1, wherein each coil group of said firstwinding layer is comprised of five coils arranged in a concentricpattern and each coil group of said second winding layer is comprised offive coils arranged in a concentric pattern, wherein three coils of saidsecond first phase coil group overlap three coils of said first firstphase coil group, wherein three coils of said second second phase coilgroup overlap three coils of said first second phase coil group, whereinthree coils of said second third phase coil group overlap three coils ofsaid first third phase coil group, wherein three coils of said fourthfirst phase coil group overlap three coils of said third first phasecoil group, wherein three coils of said fourth second phase coil groupoverlap three coils of said third second phase coil group, and whereinthree coils of said fourth third phase coil group overlap three coils ofsaid third third phase coil group.
 18. The three-phase, four poleelectric motor of claim 1, wherein each coil group of said first windinglayer is arranged in a lap winding pattern, wherein there is no overlapbetween individual coil groups comprising said first winding layer,wherein said first winding layer fills a lower portion of every slot ofsaid plurality of slots, wherein each coil group of said second windinglayer is arranged in a lap winding pattern, wherein there is no overlapbetween individual coil groups comprising said second winding layer, andwherein said second winding layer fills an upper portion of every slotof said plurality of slots.
 19. The three-phase, four pole electricmotor of claim 18, wherein each coil group of said first and secondwinding layers is comprised of a plurality of coils, wherein each ofsaid plurality of coils for each coil group is a single turn coil. 20.The three-phase, four pole electric motor of claim 18, wherein each coilgroup of said first and second winding layers is comprised of a set offive coils, wherein each coil of each set of five coils is a single turncoil.